Light emitting array structure and display

ABSTRACT

Disclosed is a light-emitting array structure having a substrate, a plurality of light-emitting pixel units, a plurality of first signal wires, a plurality of second signal wires, and an encapsulating layer. The light-emitting pixel units are arranged in array on the substrate. Each light-emitting pixel unit includes a driving chip, a first flat layer, a first redistribution layer, a second flat layer, a second redistribution layer, and a light-emitting diode. Each first signal wire is electrically connected to a corresponding one of the first redistribution layers and extends in a first direction. The second signal wires extend in a level different from the first signal wires. Each second signal wire is electrically connected to a corresponding one of the second redistribution layers and extends in a second direction different from the first direction. The encapsulating layer covers the light-emitting pixel units, the first and second signal wires, and the substrate.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority to Taiwan Application Serial Number109132460, filed Sep. 18, 2020, which is herein incorporated byreference.

BACKGROUND Field of Invention

The present disclosure relates to a light-emitting array structure and adisplay.

Description of Related Art

The mass transfer of micro-LEDs and micro-ICs and electricallyconnecting them via a redistribution layer (RDL) covering thereon toform a display pixel array are processes well known in the art. However,the structure has the disadvantage of being difficult to be repaired.For example, if there is a need to replace a defected micro-LED ormicro-IC, the defected micro-LED or micro-IC cannot be removed as theRDL is disposed thereon. In the case where a new micro-LED or micro-ICis installed after destroying the RDL, the destroyed RDL has to berecovered afterwards. However, it is difficult to apply the method onthe RDL manufactured by using the photolithography technique, and thecost is tremendously high.

Moreover, it is difficult to perform binning based on thecharacteristics of micro-LEDs beforehand when the mass transfertechnique is used for bonding micro-LEDs. As a result, the formed pixelarray is likely to have an uneven color or uneven brightness.

SUMMARY

In view of this, one goal of the present disclosure is to provide alight-emitting array structure capable of addressing the aforementionedissues.

To achieve the goal, one aspect of the present disclosure is to providea light-emitting array structure comprising a substrate, a plurality oflight-emitting pixel units, a plurality of first signal wires, aplurality of second signal wires, and an encapsulating layer. Thelight-emitting pixel units are arranged in array on the substrate. Eachof the light-emitting pixel units comprises a driver chip, a first flatlayer, a first redistribution layer, a second flat layer, a secondredistribution layer, and a light-emitting diode. The driver chip isdisposed on the substrate. The first flat layer is disposed on thesubstrate and covers the driver chip. The first redistribution layer isdisposed on the first flat layer and electrically connected to thedriver chip. The second flat layer is disposed on the first flat layerand covers the first redistribution layer. The second redistributionlayer is disposed on the second flat layer and electrically connected tothe first redistribution layer. The light-emitting diode is flip-chipbonded to and in contact with the second redistribution layer. Each ofthe first signal wires is electrically connected to a corresponding oneof the first redistribution layers and extends in a first direction. Thesecond signal wires extend in a level different from the first signalwires. Each of the second signal wires is electrically connected to acorresponding one of the second redistribution layers and extends in asecond direction different from the first direction. The encapsulatinglayer covers the light-emitting pixel units, the first signal wires, thesecond signal wires, and the substrate.

According to one embodiment of the present disclosure, the first signalwires and the first redistribution layers are located at the same level.

According to one embodiment of the present disclosure, the second signalwires and the second redistribution layers are located at the samelevel.

According to one embodiment of the present disclosure, the firstdirection is substantially perpendicular to the second direction.

According to one embodiment of the present disclosure, thelight-emitting array structure further comprises a reflective layerdisposed on a top surface of each of the second flat layers.

According to one embodiment of the present disclosure, the reflectivelayer comprises a silver reflector, an aluminum reflector, or adistributed Bragg reflector.

According to one embodiment of the present disclosure, each of thesecond redistribution layers has an upper surface, and the upper surfaceis a blackened surface.

According to one embodiment of the present disclosure, each of the firstsignal wires has an upper surface, and the upper surface is a blackenedsurface.

According to one embodiment of the present disclosure, each of thesecond signal wires has an upper surface, and the upper surface is ablackened surface.

Another aspect of the present disclosure is to provide a displaycomprising a driver substrate and a plurality of the aforementionedlight-emitting array structures. The light-emitting array structures aredisposed on the driver substrate.

BRIEF DESCRIPTION OF THE DRAWINGS

The disclosure can be more fully understood by reading the followingdetailed description of the embodiment, with reference made to theaccompanying drawings as follows.

FIG. 1 illustrates a schematic top view of a light-emitting arraystructure according to one embodiment of the present disclosure.

FIG. 2 illustrates a schematic side view of the light-emitting arraystructure according to one embodiment of the present disclosure.

FIG. 3 illustrates a schematic side view of a light-emitting arraystructure according to another embodiment of the present disclosure.

FIG. 4 illustrates a schematic top view of a display according to oneembodiment of the present disclosure.

FIG. 5 illustrates a schematic view of a display package according toanother embodiment of the present disclosure.

DETAILED DESCRIPTION

The following disclosure provides many different embodiments, orexamples, for implementing different features of the provided subjectmatter. Specific examples of components and arrangements are describedbelow to simplify the present disclosure. These are, of course, merelyexamples and are not intended to be limiting. The embodiments disclosedbelow may be combined or substituted with each other under beneficialcircumstances, and other embodiments may also be added to an embodimentwithout further description.

In the following description, certain specific details are set forth inorder to provide a thorough understanding of various embodiments of thedisclosure. However, one skilled in the art will understand that thedisclosure may be practiced without these specific details. Furthermore,for simplifying the drawings, some of the conventional structures andelements are shown with schematic illustrations.

FIG. 1 illustrates a schematic top view of a light-emitting arraystructure 10 according to one embodiment of the present disclosure. FIG.2 illustrates a schematic side view of the light-emitting arraystructure according to one embodiment of the present disclosure.Reference is made to FIG. 1 and FIG. 2 . The light-emitting arraystructure 10 includes a substrate 110, a plurality of light-emittingpixel units 120, a plurality of first signal wires 130, a plurality ofsecond signal wires 140, and an encapsulating layer 150. In variousexamples, the substrate 110 may be an aluminum substrate with a highthermal conductivity coefficient, a flexible substrate, a glasssubstrate, a metal composite laminate, a ceramic substrate, or asemiconductor substrate with functional components such as transistorsor integrated circuits (ICs).

In various examples, the substrate 110 further includes a conductive via112, a first conductive pad 114, and a second conductive pad 116.Specifically, the conductive via 112 penetrates the substrate 110 froman upper surface 110 a to a lower surface 110 b. The first conductivepad 114 and the second conductive pad 116 are disposed over the uppersurface 110 a and the lower surface 110 b of the substrate 110respectively and in contact with the conductive via 112. In someexamples, the conductive via 112 is made of copper or other conductivematerials, such as silver, nickel, tin, aluminum, or the like, but isnot limited thereto. In some examples, a through-hole penetrating thesubstrate 110 from the upper surface 110 a to the lower surface 110 bmay be first formed by using laser drilling, chemical drilling,mechanical drilling or other suitable methods. Next, the through-hole isfilled with a conductive material to form the conductive via 112. Insome examples, the first conductive pad 114 and the second conductivepad 116 are made of copper or other conductive materials, such as gold,silver, palladium, nickel, tin, aluminum, or the like, but is notlimited thereto.

Reference is still made to FIG. 1 and FIG. 2 . A plurality oflight-emitting pixel units 120 are arranged in array on the substrate110. Specifically, each of the light-emitting pixel units 120 includes adriver chip 121, a first flat layer 122, a first redistribution layer123, a second flat layer 124, a second redistribution layer 125 and alight-emitting diode 126. More specifically, the driver chip 121 isdisposed on the substrate 110.

In various examples, the driver chip 121 in the present disclosure maybe such as a mini-driver chip with a size ranging from about 1 μm to 300μm. Specifically, the size of the mini-driver chip may be such as 10 μm,30 μm, 50 μm, 70 μm, 100 μm, 120 μm, 150 μm, 200 μm, or 250 μm. It isunderstood that power supply pins of the driver chip 121 may beconnected to an output end of a power supply circuit to receive thepower supply, while driving pins of the driver chip 121 may be connectedto the light-emitting diode 126 to control the operation of the circuitof the light-emitting diode. In various examples, the driver chip 121has an over-temperature protection (OTP) function. For example, when theinternal temperature of the driver chip 121 exceeds a predeterminedtemperature (for example, 100° C.), a protection function, such asturning off the driver chip 121 to stop receiving the power supply, isactivated.

Reference is still made to FIG. 1 and FIG. 2 . More specifically, thefirst flat layer 122 is disposed on the substrate 110 and covers thedriver chip 121. In various examples, the first flat layer 122 maycomprise an oxide layer or a photosensitive insulating material, such asa photoresist material containing epoxy. In various examples, the firstflat layer 122 may be formed by using coating, spray-coating, printingor other suitable methods.

Reference is still made to FIG. 1 and FIG. 2 . More specifically, thefirst redistribution layer 123 is disposed on the first flat layer 122and electrically connected to the driver chip 121. In some examples, thefirst redistribution layer 123 comprises copper, nickel, gold, aluminum,silver or other suitable metals. In some other examples, the firstredistribution layer 123 may comprise aluminum-copper alloy,aluminum-silicon-copper alloy, or other alloys. In some examples, thefirst redistribution layer 123 may be formed on the first flat layer 122by using a deposition process such as sputtering, evaporating,electroplating or other suitable deposition processes, followed by aperforming photolithography process and an etching process. In anotherexample, a roughening process may be performed on the surface of thefirst flat layer 122, such that an excellent binding force is providedbetween the first redistribution layer 123 and the first flat layer 122.

Reference is still made to FIG. 1 and FIG. 2 . More specifically, thesecond flat layer 124 is disposed on the first flat layer 122 and coversthe first redistribution layer 123. In various examples, the materialand the manufacturing method of the second flat layer 124 may be thesame or similar to those of the first flat layer 122 and therefore arenot repeated herein.

Reference is still made to FIG. 1 and FIG. 2 . More specifically, thesecond redistribution layer 125 is disposed on the second flat layer 124and electrically connected to the first redistribution layer 123. Invarious examples, the material and the manufacturing method of thesecond redistribution layer 125 may be the same or similar to those ofthe first redistribution layer 123 and therefore are not repeatedherein. In various examples, an upper surface of the secondredistribution layer 125 is a blackened surface. In this design, theproportion of the blackened area in the light-emitting array structure10 is increased to prevent users from seeing.

Reference is still made to FIG. 1 and FIG. 2 . More specifically, thelight-emitting diode 126 is flip-chip bonded to and in contact with thesecond redistribution layer 125. In this design, the light-emittingdiode 126 is not covered by any wires, and therefore the light emissionefficiency thereof is not affected. In various examples, thelight-emitting diode 126 may be a red light-emitting diode, a greenlight-emitting diode, a blue light-emitting diode, a yellowlight-emitting diode, a white light-emitting diode, and combinationsthereof. In some examples, the light-emitting diode 126 may be amini-LED or a micro-LED. Although each of the light-emitting pixel units120 in FIG. 1 merely includes three light-emitting diodes 126, thenumber of the light-emitting diode 126 can be increased to, for example,four, five, six, seven, or above, depending on design requirements.

Since the light-emitting diode 126 and the driver chip 121 are locatedat different levels in the design of the light-emitting pixel units 120in the present disclosure, the position of the light-emitting diode 126is not limited by the position of the driver chip 121 and vice versa. Invarious examples, the light-emitting diode 126 has a vertical projectionoverlaps with a vertical projection of the driver chip 121. In thisdesign, the light-emitting diode 126 can be arranged at the centerwithout affecting the light emission symmetry of the light-emittingpixel units 120, such that an improved optical effect is achieved. Inanother example, depending on design requirements on light emission, thevertical projection of the light-emitting diode 126 may not overlap withthe vertical projection of the driver chip 121.

Reference is still made to FIG. 1 and FIG. 2 . Each of the first signalwires 130 is electrically connected to a corresponding one of the firstredistribution layers 123 and extends in a first direction D1. Invarious examples, the first signal wires 130 may comprisealuminum-copper alloy, aluminum-silicon-copper alloy, or other alloys.In some examples, the first signal wires 130 may be formed on the firstflat layer 122 by using a deposition process such as sputtering,evaporating, electroplating or other suitable deposition processes,followed by performing a photolithography process and an etchingprocesses. Therefore, it is understood that the first signal wires 130and the first redistribution layer 123 are on the same level. In variousexamples, an upper surface of each of the first signal wires 130 is ablackened surface. In this design, the proportion of the blackened areain the light-emitting array structure 10 is increased to prevent usersfrom seeing.

Reference is still made to FIG. 1 and FIG. 2 . A plurality of secondsignal wires 140 extend in a level different from the first signal wires130. More specifically, each of the second signal wires 140 iselectrically connected to a corresponding one of the secondredistribution layers 125 and extends in a second direction D1 differentfrom the first direction D1. In various examples, the second signalwires 140 may comprise aluminum-copper alloy, aluminum-silicon-copperalloy, or other alloys. In some examples, the second signal wires 140may be formed on the second flat layer 124 by using a deposition processsuch as sputtering, evaporating, electroplating or other suitabledeposition processes, followed by performing a photolithography processand an etching processes. Therefore, it is understood that the secondsignal wires 140 and the second redistribution layer 125 are at the samelevel in various examples. In various examples, the first direction D1is substantially perpendicular to the second direction D2. In variousexamples, an upper surface of each of the second signal wires 140 is ablackened surface. In this design, the proportion of the blackened areain the light-emitting array structure 10 is increased to prevent usersfrom seeing.

Reference is still made to FIG. 1 and FIG. 2 . The light-emitting pixelunits 120, the first signal wires 130, the second signal wires 140 andthe substrate 110 are covered by the encapsulating layer 150. In variousexamples, the encapsulating layer 150 may comprise an organic packagingmaterial, an inorganic packaging material or combinations thereof. Forexample, the organic packaging material comprises silicon rubber,acrylic and epoxy resin, while the inorganic packaging materialcomprises silicon dioxide and fluorine adhesive. However, the presentdisclosure is not limited thereto. In some embodiments, theencapsulating layer 150 may be formed by dispensing, molding,glue-filling or other suitable processes. The encapsulating layer 150can increase the area capable to block moisture and protect thelight-emitting array structure 10 from moisture, thereby increasing thereliability and service life of the product.

In some examples, an additive (not shown) may further be added to theencapsulating layer 150 to conceal wires and increase the brightness oflight-emitting elements. For example, the additive may be organicparticles or inorganic particles, such as ceramic particles, metalparticles, glass particles and polymer particles, and the like.

FIG. 3 illustrates a schematic side view of a light-emitting arraystructure 30 according to another embodiment of the present disclosure.In order to facilitate the comparison with the aforementionedembodiments and simplify the description, the same reference numbers areused in the following embodiments to refer to the same or like parts.Also, the differences between embodiments are discussed below andsimilar parts will not be repeated.

The light-emitting array structure 30 is different from thelight-emitting array structure 10 as the light-emitting array structure30 further comprises a reflective layer 310 disposed on a top surface ofthe second flat layer 124. In various examples, the reflective layer 310may be a silver reflector, an aluminum reflector or a distributed Braggreflector (DBR). Specifically, the distributed Bragg reflector may becomposed of two or more thin films stacked alternatively, in which thethin films are homogenous or heterogeneous materials with differentrefractive indices. For example, the distributed Bragg reflector may becomposed of alternatively stacked SiO₂ and TiO₂ thin films oralternatively stacked SiO₂/Al₂O₃/TiO₂ thin films. This design canincrease the light emission efficiency of the light-emitting arraystructure 30.

FIG. 4 illustrates a schematic top view of a display 40 according to oneembodiment of the present disclosure. As shown in FIG. 4 , the display40 comprises a driver substrate 410 and the light-emitting arraystructure 10 or 30 as described above. The light-emitting arraystructure 10 or 30 is disposed on the driver substrate 410. In variousexamples, the driver substrate 410 may be such as a light board, alight-emitting diode array substrate, or a circuit board. As one or moreof the light-emitting pixel units 120 are defective, the light-emittingarray structure 10 or 30 can be replaced entirely, thereby simplifyingthe repair process.

FIG. 5 illustrates a schematic view of a display package 50 according toanother embodiment of the present disclosure. As shown in FIG. 5 , thelight-emitting array structure 10 shown in FIG. 1 may be diced to form aplurality of individual light-emitting pixel units 120. The individuallight-emitting pixel units 120 are subjected to binning based on theircharacteristics and are then bonded to the driver substrate 410. As oneof the light-emitting pixel units 120 is defective, the defectivelight-emitting pixel units 120 are easy to be removed and directlyreplaced. The approach not only advantages in simplifying the repairprocess, but also reduces time, material and cost for failure analysisand repair work. Furthermore, by means of binning the individuallight-emitting pixel unit 120 and then bonding the light-emitting pixelunits 120 with the same specifications to one driver substrate 410, theunevenness in visual appearance can be eliminated. Compared with thedisplay package 50 shown in FIG. 5 , the cost of package dicing,binning, surface mounting and repair of the display 40 shown in FIG. 4can be further reduced.

In summary, in the light-emitting array structure of the presentdisclosure, a plurality of flat layers are used to alleviate the leveldifference in the conventional redistribution layer, such that each ofthe redistribution layers can be flatly disposed on the flat layer andis therefore capable to maintain narrow, thin circuits with highprecision. Moreover, while manufacturing the redistribution layer,signal wires arranged in array of the display can be manufactured at thesame time to achieve the advantage of circuit integration. Furthermore,the redistribution layer has a surface flatness higher than a surfaceflatness of the substrate, such that the transfer yield for the masstransfer technique is improved. In the design in the present disclosure,a substrate with high-precision circuits is not necessary, and thelight-emitting array structure can be easily miniaturized. In addition,the display of the present disclosure is easy to repair.

Although the present disclosure has been described in considerabledetail with reference to certain embodiments thereof, other embodimentsare possible. It will be apparent to those skilled in the art thatvarious modifications and variations can be made to the structure of thepresent disclosure without departing from the scope or spirit of thedisclosure. In view of the foregoing, it is intended that the presentdisclosure cover modifications and variations of this disclosureprovided they fall within the scope of the following claims.

What is claimed is:
 1. A light-emitting array structure, comprising: a substrate; a plurality of light-emitting pixel units arranged in array on the substrate, each of the light-emitting pixel units comprising: a driver chip disposed on the substrate; a first flat layer disposed on the substrate and covers the driver chip; a layer of a plurality of first redistribution layers disposed on the first flat layer and electrically connected to the driver chip; a second flat layer disposed on the first flat layer and covers the first redistribution layers; a layer of a plurality of second redistribution layers disposed on the second flat layer and electrically connected to the layer of the plurality of first redistribution layers; and a light-emitting diode, flip-chip bonded to and in contact with the second redistribution layers; a plurality of first signal wires, wherein each of the first signal wires is electrically connected to a corresponding one of the first redistribution layers and extends in a first direction; a plurality of second signal wires extending in a level different from the first signal wires, wherein each of the second signal wires is electrically connected to a corresponding one of the second redistribution layers and extends in a second direction different from the first direction; and an encapsulating layer covering the light-emitting pixel units, the first signal wires, the second signal wires, and the substrate; wherein each of the second redistribution layers has an upper surface, and the upper surface is a blackened surface.
 2. The light-emitting array structure of claim 1, wherein the first signal wires and the first redistribution layers are located at a same level.
 3. The light-emitting array structure of claim 1, wherein the second signal wires and the second redistribution layers are located at a same level.
 4. The light-emitting array structure of claim 1, wherein the first direction is substantially perpendicular to the second direction.
 5. The light-emitting array structure of claim 1, further comprising a reflective layer disposed on a top surface of each of the second flat layers.
 6. The light-emitting array structure of claim 5, wherein the reflective layer comprises a silver reflector, an aluminum reflector, or a distributed Bragg reflector.
 7. The light-emitting array structure of claim 1, wherein each of the first signal wires has an upper surface, and the upper surface is a blackened surface.
 8. The light-emitting array structure of claim 1, wherein each of the second signal wires has an upper surface, and the upper surface is a blackened surface.
 9. A display, comprising: a driver substrate; and a plurality of light-emitting array structures of claim 1 disposed on the driver substrate. 